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Re: [Xen-devel] xen vbd: better.

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] xen vbd: better.
From: "Ronald G. Minnich" <rminnich@xxxxxxxx>
Date: Fri, 22 Oct 2004 12:50:00 -0600 (MDT)
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On Fri, 22 Oct 2004, Keir Fraser wrote:

> How can you get any low-level systems work done without supporting
> data interoperability via packed structs? How can you define sane
> network header structs for example? You can't know that your compiler
> won't pack your IP header layout incorrectly!

it's interesting to see the very different thoughts in the Plan 9
community (Ken included) about this issue. Basic feeling over there is
that putting packed structs into the compiler is a terrible idea, not
needed, it's deprecated, and should never be used. That's my polite
translation :-)

Plan 9 works just fine without packed structs, as do the many operating 
systems written by people using compilers that didn't do packed structs 
either, or even compilers that always packed structs (V6  C). All these 
systems twiddled bits just fine. 

Anyways, I'll stick with unpacking and packing them myself. Here's an 
interesting cultural issue (at least to me) brought up by a simple 
compiler switch!

ron


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